Resilient plunger clamp



Oct. 19, 1965 H. c. ROBESON 3,212,347

RESILIENT PLUNGER CLAMP Filed NOV. 13, 1962 INVENTOR.

HARE/JON C #054550 United States Patent 3,212,347 RESILIENT PLUNGERCLAMP Harrison C. Robeson, Birmingham, Mich, assignor to De- Sta-CoCorporation, Detroit, Mich, a corporation of Michigan Filed Nov. 13,1962, Ser. No. 237,118 Claims. (Cl. 74-406) This invention relates to atoggle-actuated plunger clamp and more particularly to a plunger clampincorporating a resilient element in the linkage which automaticallycompensates for thickness variations in castings, forgings and similarproduction parts which the clamp is adapted to hold as in productionprocessing.

One object of the invention is to adapt a standard clamp to incorporatesuch resilient feature with a minimum of modification. Another object isto completely enclose the resilient mechanism to keep it free from dirt,chips and weld spatter.

These and other objects will be more apparent from the followingdetailed description of a preferred embodiment of the invention withreference to the drawings disclosing the same wherein:

FIGURE 1 is a side elevation of a conventional plunger clamp;

FIGURE 2 is a plan View of said clamp;

FIGURE 3 is an end elevation of said clamp; and

FIGURE 4 is a fragmentary side elevation showing a modified constructionincorporating the resilient feature of the present invention.

Referring to FIGS. 1, 2 and 3 the conventional clamp comprises a basehaving a cylindrical plunger guide 11 and a vertical boss pivotalconnection 12 mounting a clamp handle 13 having a second pivotalconnection 14 with a pair of side link elements 15 in turn pivotallyconnected at 16 to a generally cylindrical plunger 17, the open positionof the clamp elements being shown in dotted line in FIG. 1. The toggleaction provided by closing the clamp handle to bring the central pivot14 into alignment between the rear pivot 12 and the forward pivot 15moves the plunger 17 into pressure engagement with a workpiece to beheld (not shown).

As shown in FIG. 4 a resilient feature is incorporated by providing acylindrical end bore 18 in the pivot end of the plunger 17 in which acompression spring 19 is inserted and pre-compressed upon insertion ofthe pivot pin 20. A pivot pin slot 21 of suitable length is provided toaccommodate back travel of the plunger further compressing spring 19.Thus a part thickness variation equal to the length of slot 21 isaccommodated with a minimum clamping pressure equal to thepro-compression of spring 19 in the assembled condition shown.

While a particular preferred embodiment has been shown and describedabove in detail it will be understood that certain modifications mightbe resorted to without departing from the scope of this invention asdefined in the following claims.

I claim:

1. A toggle plunger clamp comprising a base, a fixed plunger guide onsaid base, a compression clamp plunger confined by said guide tostraight line reciprocating movement toggle linkage pivotally connectedto one end of said plunger, a transverse pivot pin forming the pivotalconnection between said toggle linkage and said plunger, a helicalcompression spring seated within said plunger reacting at one endagainst said pivot pin, and an enlarged transverse slot in said plungerforming a seat for said pivot pin, said slot accommodating limitedtravel of said plunger along said line relative to said pivot pinagainst compressive resistance of said spring.

2. A toggle clamp as set forth in claim 1 wherein said plunger comprisesa cylindrical element having an axial bore extending to a limited depthfrom one end for housing said compression spring.

3. A toggle clamp as set forth in claim 2 wherein said transverse slotis elongated in the direction of the axis of said plunger and helicalcompression spring.

4. A toggle clamp as set forth in claim 3 wherein said toggle linkage isactuated by a handle pivotally connected to said linkage with atransverse pivotal axis substantially intersecting an extension of saidplunger and helical spring axis when said toggle clamp is in closedposition.

5. A toggle clamp as set forth in claim 4 wherein said handle element ispivotally connected to said base with another transverse pivotalconnection also substantially intersecting an extension of the axis ofsaid plunger and helical compression spring.

References Cited by the Examiner UNITED STATES PATENTS 912,277 2/09Benson 7452O 1,951,212 3/34 Sawatzky 7439 2,514,839 7/50 CaSWell 74-106X 2,574,281 11/51 Olson 74106X BROUGHTON G. DURHAM Primary Examiner.

1. A TOGGLE PLUNGER CLAMP COMPRISING A BASE, A FIXED PLUNGER GUIDE ON SAID BASE, A COMPRESSION CLAMP PLUNGER CONFINED BY SAID GUIDE TO STRAIGHT LINE RECIPROCATING MOVEMENT TOGGLE LINKAGE PIVOTALLY CONNECTED TO ONE END OF SAID PLUNGER, A TRANSVERSE PIVOT PIN FORMING THE PIVOTAL CONNECTING BETWEEN SAID TOGGLE LINKAGE AND SAID PLUNGER, A HELICAL COMPRESSION SPRING SEATED WITHIN SAID PLUNGER REACTING AT ONME END AGAINST SAID PIVOT PIN, AND AN ENLARGED TRANSVERSE SLOT IN SAID PLUNGER FORMING A SEAT FOR SAID PIVOT PIN, SAID SLOT ACCOMMODATING LIMIT LEVEL OF SAID PLUNGER ALONG SAID LINE RELATIVE TO SAID PIVOT PIN AGAINST COMPRESSIVE RESISTANCE OF SAID SPRING. 